Exhaust silencer

The exhaust or exhaust silencer is fitted to internal-combustion engines in order to muffle exhaust noise. All cars, motorcycles, scooters and trucks circulating on the road now feature a standard exhaust silencer in order to comply with the laws on noise emissions. The exhaust silencer fitted to road vehicles must necessarily be type-approved by the traffic control authority. Worksite machinery, operating machines and power generators are also equipped with exhaust silencers. The exhaust silencer is generally integrated in the exhaust system itself. The fitting of an exhaust silencer to the exhaust line often causes load loss, above all in the case of super silencers, where a high degree of noise muffling is required. The silencing method normally used to make exhaust silencers is that of absorption and is tied to the use of sound-dampening materials (such as glass wool, rock wool or stainless-steel wire wool). The size of the exhaust silencer will depend on the type of engine and on its power and displacement, but is often also tied to the degree of noise muffling which the silencer has to achieve. Exhaust silencers are normally made of carbon steel treated on the outside with paints resistant to the high temperatures of exhaust gases. For special applications, exhaust silencers can also be made of stainless steel; this is the case for instance of exhaust silencers fitted to boats. In these cases, stainless steel has to be used to prevent any possible corrosion by seawater. Exhaust silencers are often also made of stainless steel to cater for special aesthetic requirements; this is the case for instance of exhaust silencer end pieces on trucks and motorcycles.